ROTJ is a great film. I don't find it as good as ESB or ANH, but it is certainly great. As a kid I wore out all 3 of my OT VHS tapes, but never found ROTJ to be as exciting or well paced as the other two. I also has a hard time believing ewoks could help defeat the Empire.
As to it being thought of as a lesser film than AOTC or ROTS is a new one on me, and its got nothing to do with there being a love story (ESB?), or merchandising-friendly characters in the PT, its just that I don't believe in any of the characters because the acting is so terrible, McDiarmid excluded. I cared about the OT characters and didn't want any of them to die. Watching the PT I couldn't care less if they did die. I often find myself watching the excessive clutter in the background of every single frame because I find the actors' performances so two-dimensional most of the time.